1. Field of the Invention
The system of the present invention relates to the field of radio telephones. Specifically the system of the present invention relates to a multi-user radio telephone system which operates in a proximal environment.
2. Art Background
Use of radio or "cordless" telephones have become quite popular because they give the user of the radio telephone mobility previously not had with a corded telephone. Such telephones are easily found on the commercial market, and have enjoyed widespread use. Typically, such cordless phones are connected individually to the central office telephone lines through a base unit physically connected to the telephone lines which connect to the central office. The base unit also contains a radio transceiver to transmit the voice information to the cordless handset and receive radio transmissions containing voice information from the handset. In a business environment, a business typically operates its own local telephone network within the office to provide such capabilities as intercom between phones, conferencing among phones, as well as to minimize the number of required central office lines to service all the phone users in the office (because not all users use the phone simultaneously). Most businesses use a private branch exchange (PBX) or multiple line key system (Key) to perform these functions.
The limitations of a corded system in a business environment is quite evident. The relocation of offices requires a change of phone number or reconfiguration/rewiring of the telephone system to move the phone to a different location. Furthermore, work efficiency is decreased by not being available near the office phone when incoming calls arrive. However, difficulties arise in providing the functionality of corded telephones to the radio telephones. The information used to control the status of the phone system must be operated in a real time manner and communicated to the cordless handsets in a real time manner in order to provide full functionality that the corded handsets provide in a sophisticated business telephone system. Furthermore, this sophisticated functionality must be provided while maintaining voice transmission quality. However, it has been found that due to the amount of functionality required, such systems are difficult to design and implement. Typically the user will experience degradation in telephone sound quality and/or slight delays between transmissions in order to increase the functionality of the system.
The use of a telephone conferencing capability has become a popular means for more than two people to communicate concurrently over the phone. However a telephone system's conferencing capability is typically limited to a few users in the number that can be conferenced during a call due to the amount of circuitry and system overhead required to support a conferencing capability. Additional conferencing circuits have been implemented with "conference bridges" that externally attach to ports on a PBX or Key system. Each port corresponds to a participant in the conference. Therefore, for a four party conference call, four additional analog ports on the PBX or Key system are required to accommodate all conference participants, only one conference call can take place per conference bridge and four analog ports are dedicated to this function.
Though newer implementations of conference circuits perform conferencing internally (some even do it digitally), there is still one (or more) dedicated pieces of hardware that performs "a conference". If more than one simultaneous conferences are desired, more dedicated hardware must be added. Each of these conference circuits, takes up either a physical port or a "time-slot" per conference participant. These systems are limited by either the number of conference participants or the number of simultaneous conferences that can be in progress at any one time.